Cantelowes Gardens in Camden, north London, is bustling with "Skate Betties" - the term used by male skateboarders for girls who hang around skate parks. They're hunting in packs of at least six, tugging on illicit ciggies, eyeing up the lads pulling tricks in the sunshine. They wear little make-up and their hair is tightly cropped, adorned with sparkly clips. Oversized baggy FUBU trousers hang low on slim hips, dog chains slung from front to back pocket, and tight pink Ts bare midriffs. A mobile phone is passed around and reports on the state of the talent.

Skateboarding has never been bigger. It's now huge money. Today Eurosport and Channel 5 will cover the final of the UK leg of the World Cup Skateboarding at Radlands in Northampton, just one of 15 official dates worldwide. In America, satellite broadcaster ESPN is heavily involved with the X Games competition, rebroadcast in the UK on Channel 4. Top professional skaters - whose ranks have swelled to over 200 - can earn six-figure incomes from appearance fees and sponsorship deals.

Yet the Skate Betties - Betties for short - were the only female contingent at last Sunday's Cantelowes Skate Jam. There were no women skating. The sight of a female skateboarder remains a rarity. And the few that do exist have very little time for the Betties.

"I don't understand where they're coming from," says 19-year-old girl skater LJ. "Girl skaters and Betties don't get on. They always try to jinx us. When you fall over, they're the first to laugh. They're jealous. They don't like it that we can skate and get on with the boys. If you're real you know who's a skater and who's dressing the part."

The Betties aren't the only ones dressing the part. The influence of skate culture has been acutely felt in the high street. From yesterday's Vans trainers (worn by All Saints) to today's drawstring trousers (also worn by All Saints), teenage girls can't get enough. "It reflects the lifestyle the kids live now," says J17's fashion and beauty editor, Teresa Letchford. "It's functional, streetwise, sassy. It crosses all the boundaries of colour and class. It's what the kids are about - it doesn't matter who you are. Teetering in stilettos isn't very girl power."

So why do so few girls make the transition from Top Shop to skateboard? After all, if the Betties spent even half their time down the park practising, they'd be more than proficient, reckons LJ.

Ask most boys in the park, and you're met with an assertion that skating isn't for girls. Perhaps therein lies the answer. Louise Maxwell, who's been skating for two years, agrees that it is very intimidating "performing" - or falling on your arse - in front of the lads.

Her explanation for why girls don't skateboard is rather antiquated - "girls aren't natural risk-takers". Skaters risk serious injury and at the very least regular painful falls. Dedicated skaters can be identified by the scars on their forearms, "swellbows" (broken and mangled elbows), "shinners" (dents in their shin bones) and broken hands and fingers. (Nobody wears protective pads.)

"Whenever anyone skates for the first time, the chances are they'll really hurt themselves," says Louise. "But because boys have bigger egos and are so susceptible to peer pressure they persevere." In snowboarding, where there's less risk of injury, the male to female ratio is 70:30 to skating's 99:1.

Elissa Steamer is that one-in-a- hundred female skater - one of only two female professionals in the world. Her appearance puts paid to one of the more absurd explanations for the absence of female skaters: that girls don't have the build for it. She is slight, with skinny arms and a nervous handshake.

Although she has skated in all the recent Girls' Skateboard Association jams in America, she refuses to single herself out. "Being a skateboarder isn't about being a girl or a boy," she says. "Of course, I'm female, but it shouldn't be an issue. My peers treat me normally. Girls tell me I'm their inspiration, but I shouldn't be. If they want to skate they should. Period."

Skaters are notoriously uncompromising, which perversely has only served to heighten commercial interest. They have consistently avoided being assimilated into the mainstream - which inevitably makes them attractive to brand managers, marketing men, advertisers and public relations. Being one of only two female pros while so many teenage girls' eyes are focusing on the sport is no bad thing.

Since turning pro a year ago, Elissa has landed several sponsorship deals and is making a good living skating for cash prizes. She will be one of 10 pros featured in a new computer simulator game for PlayStation. Rumours abound she's about to start seeing some serious money with a "signature" shoe deal: a pro has reputably earned $4 from every one of 140,000 signature shoes his sponsor has sold to date.

Alex Weller, from youth PR firm Third Planet, and a dedicated skater, reckons that, for most, the increasing financial interest "will be like water off a duck's back": "Real skaters will only get angry about brands doing things autonomously, claiming they're part of it without showing any long-term commitment." It's a fine line between sponsoring the sport and exploitation. Be assured, skaters will run a mile if they suspect anyone has stepped over that line.

Meanwhile, back at the G-Shock Cantelowes Skate Jam, some boarders debate the Bettie phenomenon. The odd girl has always been a fixture at skate parks, but it's got silly, they reckon. You can't move for gangs of them, and they're getting younger and younger. "Some are horny, but they're jailbait," comments one 18-year- old. "Take her, for example. She's special, but you wouldn't do three to four [years in prison for statutory rape] for it," he says, to general amusement. "We're just here to skate." With that, he scoots off and pulls a neat jump in front of a trio of doe-eyed girls.

He may not have too much to worry about. By now, most of the Betties have lost interest in the skating and sit with their backs to the ramps. Sure, some of the skaters are cute, but they just want to skate, they complain. We mostly come down here to catch up with each other and hang out, is the consensus.

Perhaps, it's a fashion thing. They've got the drawstring pants, the dog chain, so why not show them off? Like girls of their age 10 years ago, waiting outside hotels for a glimpse of Take That, perhaps it's more about camaraderie than sex - or skateboarding.